What should I do if the bus door won't close?

When a bus door won't close, the worst thing is for the driver to repeatedly press the switch in a panic. Passengers are standing and waiting, and traffic behind is honking, but if the door system is already jammed, forcing it shut can make the problem worse. Common causes aren't always a broken door; sometimes it's a small pebble stuck in the door track, deformed rubber seals, or the…